Mechanoregulation of intracellular Ca2+ concentration is attenuated in collecting duct of monocilium-impaired orpk mice

2005 ◽  
Vol 289 (5) ◽  
pp. F978-F988 ◽  
Author(s):  
Wen Liu ◽  
Noel S. Murcia ◽  
Yi Duan ◽  
Sheldon Weinbaum ◽  
Bradley K. Yoder ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Primary Cilia ◽  
Collecting Duct ◽  
Polycystic Kidney ◽  
New Findings ◽  
Collecting Ducts ◽  
Before And After ◽  
Luminal Flow

Autosomal recessive polycystic kidney disease (ARPKD) is characterized by the progressive dilatation of collecting ducts, the nephron segments responsible for the final renal regulation of sodium, potassium, acid-base, and water balance. Murine models of ARPKD possess mutations in genes encoding cilia-associated proteins, including Tg737 in orpk mice. New findings implicate defects in structure/function of primary cilia as central to the development of polycystic kidney disease. Our group (Liu W, Xu S, Woda C, Kim P, Weinbaum S, and Satlin LM, Am J Physiol Renal Physiol 285: F998–F1012, 2003) recently reported that increases in luminal flow rate in rabbit collecting ducts increase intracellular Ca2+ concentration ([Ca2+]i) in cells therein. We thus hypothesized that fluid shear acting on the apical membrane or hydrodynamic bending moments acting on the cilium increase renal epithelial [Ca2+]i. To further explore this, we tested whether flow-induced [Ca2+]i transients in collecting ducts from mutant orpk mice, which possess structurally abnormal cilia, differ from those in controls. Isolated segments from 1- and 2-wk-old mice were microperfused in vitro and loaded with fura 2; [Ca2+]i was measured by digital ratio fluorometry before and after the rate of luminal flow was increased. All collecting ducts responded to an increase in flow with an increase in [Ca2+]i, a response that appeared to be dependent on luminal Ca2+ entry. However, the magnitude of the increase in [Ca2+]i in 2- but not 1-wk-old mutant orpk animals was blunted. We speculate that this defect in mechano-induced Ca2+ signaling in orpk mice leads to aberrant structure and function of the collecting duct in ARPKD.

scholarly journals Discovery and preclinical evaluation of anti-miR-17 oligonucleotide RGLS4326 for the treatment of polycystic kidney disease

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Edmund C. Lee ◽  
Tania Valencia ◽  
Charles Allerson ◽  
Annelie Schairer ◽  
Andrea Flaten ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Collecting Duct ◽  
Treatment Options ◽  
Subcutaneous Administration ◽  
Polycystic Kidney ◽  
Short Oligonucleotide ◽  
Mrna Targets ◽  
Stage Renal Disease

Abstract Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in either PKD1 or PKD2 genes, is one of the most common human monogenetic disorders and the leading genetic cause of end-stage renal disease. Unfortunately, treatment options for ADPKD are limited. Here we report the discovery and characterization of RGLS4326, a first-in-class, short oligonucleotide inhibitor of microRNA-17 (miR-17), as a potential treatment for ADPKD. RGLS4326 is discovered by screening a chemically diverse and rationally designed library of anti-miR-17 oligonucleotides for optimal pharmaceutical properties. RGLS4326 preferentially distributes to kidney and collecting duct-derived cysts, displaces miR-17 from translationally active polysomes, and de-represses multiple miR-17 mRNA targets including Pkd1 and Pkd2. Importantly, RGLS4326 demonstrates a favorable preclinical safety profile and attenuates cyst growth in human in vitro ADPKD models and multiple PKD mouse models after subcutaneous administration. The preclinical characteristics of RGLS4326 support its clinical development as a disease-modifying treatment for ADPKD.

scholarly journals Disrupting polycystin-2 EF hand Ca2+ affinity does not alter channel function or contribute to polycystic kidney disease

2020 ◽  
Vol 133 (24) ◽  
pp. jcs255562
Author(s):  
Thuy N. Vien ◽  
Leo C. T. Ng ◽  
Jessica M. Smith ◽  
Ke Dong ◽  
Matteus Krappitz ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Primary Cilia ◽  
Collecting Duct ◽  
Mouse Strains ◽  
Polycystic Kidney ◽  
Channel Function ◽  
Ef Hand ◽  
Voltage Dependent ◽  
Autosomal Dominant Polycystic Kidney

ABSTRACTApproximately 15% of autosomal dominant polycystic kidney disease (ADPKD) is caused by variants in PKD2. PKD2 encodes polycystin-2, which forms an ion channel in primary cilia and endoplasmic reticulum (ER) membranes of renal collecting duct cells. Elevated internal Ca2+ modulates polycystin-2 voltage-dependent gating and subsequent desensitization – two biophysical regulatory mechanisms that control its function at physiological membrane potentials. Here, we refute the hypothesis that Ca2+ occupancy of the polycystin-2 intracellular EF hand is responsible for these forms of channel regulation, and, if disrupted, results in ADPKD. We identify and introduce mutations that attenuate Ca2+-EF hand affinity but find channel function is unaltered in the primary cilia and ER membranes. We generated two new mouse strains that harbor distinct mutations that abolish Ca2+-EF hand association but do not result in a PKD phenotype. Our findings suggest that additional Ca2+-binding sites within polycystin-2 or Ca2+-dependent modifiers are responsible for regulating channel activity.

scholarly journals Increased Na+/H+exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

2012 ◽  
Vol 302 (10) ◽  
pp. C1436-C1451 ◽  
Author(s):  
Dragos Olteanu ◽  
Xiaofen Liu ◽  
Wen Liu ◽  
Venus C. Roper ◽  
Neeraj Sharma ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Collecting Duct ◽  
Principal Cell ◽  
Cortical Collecting Duct ◽  
Wild Type ◽  
Polycystic Kidney ◽  
Acid Base ◽  
Collecting Ducts ◽  
Mutant Cells

Pathophysiological anomalies in autosomal dominant and recessive forms of polycystic kidney disease (PKD) may derive from impaired function/formation of the apical central monocilium of ductal epithelia such as that seen in the Oak Ridge polycystic kidney or orpk ( Ift88Tg737Rpw) mouse and its immortalized cell models for the renal collecting duct. According to a previous study, Na/H exchanger (NHE) activity may contribute to hyperabsorptive Na+movement in cilium-deficient (“mutant”) cortical collecting duct principal cell monolayers derived from the orpk mice compared with cilium-competent (“rescued”) monolayers. To examine NHE activity, we measured intracellular pH (pHi) by fluorescence imaging with the pH-sensitive dye BCECF, and used a custom-designed perfusion chamber to control the apical and basolateral solutions independently. Both mutant and rescued monolayers exhibited basolateral Na+-dependent acid-base transporter activity in the nominal absence of CO2/HCO3−. However, only the mutant cells displayed appreciable apical Na+-induced pHirecoveries from NH4+prepulse-induced acid loads. Similar results were obtained with isolated, perfused collecting ducts from orpk vs. wild-type mice. The pHidependence of basolateral cariporide/HOE-694-sensitive NHE activity under our experimental conditions was similar in both mutant and rescued cells, and 3.5- to 4.5-fold greater than apical HOE-sensitive NHE activity in the mutant cells (pHi6.23–6.68). Increased apical NHE activity correlated with increased apical NHE1 expression in the mutant cells, and increased apical localization in collecting ducts of kidney sections from orpk vs. control mice. A kidney-specific conditional cilium-knockout mouse produced a more acidic urine compared with wild-type littermates and became alkalotic by 28 days of age. This study provides the first description of altered NHE activity, and an associated acid-base anomaly in any form of PKD.

scholarly journals Gender-Dependent Phenotype in Polycystic Kidney Disease Is Determined by Differential Intracellular Ca2+ Signals

2021 ◽  
Vol 22 (11) ◽  
pp. 6019
Author(s):  
Khaoula Talbi ◽  
Inês Cabrita ◽  
Rainer Schreiber ◽  
Karl Kunzelmann
Keyword(s):  
Cell Proliferation ◽  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Collecting Duct ◽  
Primary Cells ◽  
Loss Of Function ◽  
Polycystic Kidney ◽  
Chloride Currents ◽  
Duct Cells ◽  
Collecting Duct Cells

Autosomal dominant polycystic kidney disease (ADPKD) is caused by loss of function of PKD1 (polycystin 1) or PKD2 (polycystin 2). The Ca2+-activated Cl− channel TMEM16A has a central role in ADPKD. Expression and function of TMEM16A is upregulated in ADPKD which causes enhanced intracellular Ca2+ signaling, cell proliferation, and ion secretion. We analyzed kidneys from Pkd1 knockout mice and found a more pronounced phenotype in males compared to females, despite similar levels of expression for renal tubular TMEM16A. Cell proliferation, which is known to be enhanced with loss of Pkd1−/−, was larger in male when compared to female Pkd1−/− cells. This was paralleled by higher basal intracellular Ca2+ concentrations in primary renal epithelial cells isolated from Pkd1−/− males. The results suggest enhanced intracellular Ca2+ levels contributing to augmented cell proliferation and cyst development in male kidneys. Enhanced resting Ca2+ also caused larger basal chloride currents in male primary cells, as detected in patch clamp recordings. Incubation of mouse primary cells, mCCDcl1 collecting duct cells or M1 collecting duct cells with dihydrotestosterone (DHT) enhanced basal Ca2+ levels and increased basal and ATP-stimulated TMEM16A chloride currents. Taken together, the more severe cystic phenotype in males is likely to be caused by enhanced cell proliferation, possibly due to enhanced basal and ATP-induced intracellular Ca2+ levels, leading to enhanced TMEM16A currents. Augmented Ca2+ signaling is possibly due to enhanced expression of Ca2+ transporting/regulating proteins.

scholarly journals Modeling Neoplastic Growth in Renal Cell Carcinoma and Polycystic Kidney Disease

2021 ◽  
Vol 22 (8) ◽  
pp. 3918
Author(s):  
Cassandra Millet-Boureima ◽  
Stephanie He ◽  
Thi Bich Uyen Le ◽  
Chiara Gamberi
Keyword(s):  
Renal Cell Carcinoma ◽  
Kidney Disease ◽  
Cell Carcinoma ◽  
Polycystic Kidney Disease ◽  
Renal Cell ◽  
Primary Cilia ◽  
Genetic Model ◽  
Cell Metabolism ◽  
Neoplastic Cell ◽  
Polycystic Kidney

Renal cell carcinoma (RCC) and autosomal dominant polycystic kidney disease (ADPKD) share several characteristics, including neoplastic cell growth, kidney cysts, and limited therapeutics. As well, both exhibit impaired vasculature and compensatory VEGF activation of angiogenesis. The PI3K/AKT/mTOR and Ras/Raf/ERK pathways play important roles in regulating cystic and tumor cell proliferation and growth. Both RCC and ADPKD result in hypoxia, where HIF-α signaling is activated in response to oxygen deprivation. Primary cilia and altered cell metabolism may play a role in disease progression. Non-coding RNAs may regulate RCC carcinogenesis and ADPKD through their varied effects. Drosophila exhibits remarkable conservation of the pathways involved in RCC and ADPKD. Here, we review the progress towards understanding disease mechanisms, partially overlapping cellular and molecular dysfunctions in RCC and ADPKD and reflect on the potential for the agile Drosophila genetic model to accelerate discovery science, address unresolved mechanistic aspects of these diseases, and perform rapid pharmacological screens.

scholarly journals Molecular Pathways and Therapies in Autosomal-Dominant Polycystic Kidney Disease

Physiology ◽  
2015 ◽  
Vol 30 (3) ◽  
pp. 195-207 ◽  
Author(s):  
Takamitsu Saigusa ◽  
P. Darwin Bell
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Primary Cilia ◽  
Autosomal Dominant ◽  
Molecular Pathways ◽  
Polycystic Kidney ◽  
Autosomal Dominant Polycystic Kidney ◽  
Multiple Cysts ◽  
Review Current

Autosomal-dominant polycystic kidney disease (ADPKD) is the most prevalent inherited renal disease, characterized by multiple cysts that can eventually lead to kidney failure. Studies investigating the role of primary cilia and polycystins have significantly advanced our understanding of the pathogenesis of PKD. This review will present clinical and basic aspects of ADPKD, review current concepts of PKD pathogenesis, evaluate potential therapeutic targets, and highlight challenges for future clinical studies.

Molecular genetics of renal ciliopathies

2021 ◽  
Author(s):  
Miguel Barroso-Gil ◽  
Eric Olinger ◽  
John A. Sayer
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Primary Cilia ◽  
Cystic Kidney Disease ◽  
Cystic Kidney ◽  
Renal Tubules ◽  
Polycystic Kidney ◽  
Inherited Disorders ◽  
Disease Phenotypes ◽  
Renal Histology

Renal ciliopathies are a heterogenous group of inherited disorders leading to an array of phenotypes that include cystic kidney disease and renal interstitial fibrosis leading to progressive chronic kidney disease and end-stage kidney disease. The renal tubules are lined with epithelial cells that possess primary cilia that project into the lumen and act as sensory and signalling organelles. Mutations in genes encoding ciliary proteins involved in the structure and function of primary cilia cause ciliopathy syndromes and affect many organ systems including the kidney. Recognised disease phenotypes associated with primary ciliopathies that have a strong renal component include autosomal dominant and recessive polycystic kidney disease and their various mimics, including atypical polycystic kidney disease and nephronophthisis. The molecular investigation of inherited renal ciliopathies often allows a precise diagnosis to be reached where renal histology and other investigations have been unhelpful and can help in determining kidney prognosis. With increasing molecular insights, it is now apparent that renal ciliopathies form a continuum of clinical phenotypes with disease entities that have been classically described as dominant or recessive at both extremes of the spectrum. Gene-dosage effects, hypomorphic alleles, modifier genes and digenic inheritance further contribute to the genetic complexity of these disorders. This review will focus on recent molecular genetic advances in the renal ciliopathy field with a focus on cystic kidney disease phenotypes and the genotypes that lead to them. We discuss recent novel insights into underlying disease mechanisms of renal ciliopathies that might be amenable to therapeutic intervention.

scholarly journals Functional activity of epidermal growth factor receptors in autosomal recessive polycystic kidney disease

1998 ◽  
Vol 275 (3) ◽  
pp. F387-F394 ◽  
Author(s):  
William E. Sweeney ◽  
Ellis D. Avner
Keyword(s):  
Growth Factor ◽  
Kidney Disease ◽  
Epidermal Growth Factor ◽  
Polycystic Kidney Disease ◽  
Autosomal Recessive ◽  
Apical Surface ◽  
Polycystic Kidney ◽  
High Affinity ◽  
Epidermal Growth

Evidence from a number of laboratories suggests a potential role for the epidermal growth factor (EGF)-transforming growth factor-α-epidermal growth factor receptor (EGF-R) axis in promoting epithelial hyperplasia and cyst formation in autosomal recessive polycystic kidney disease (ARPKD). As previously reported, in the C57BL-6Jcpk/cpk (CPK), BALB/c-bpk/bpk (BPK), and C3H-orpk/orpk (ORPK) murine models of ARPKD, as well as in human ARPKD and human ADPKD, the EGF-R is mislocated to the apical surface of cystic collecting tubule (CT) epithelial cells. The present studies demonstrate that cells from cystic and control CTs can be isolated and that these cells maintain their in vivo EGF-R phenotype in vitro. Domain-specific high-affinity ligand binding was assessed by standard Scatchard analysis, and selective ligand stimulation of apical vs. basolateral EGF-R in these cells was followed by measurement of receptor autophosphorylation and determination of cell proliferation. These studies demonstrate that in vitro apically expressed EGF-Rs exhibit high-affinity binding for EGF, autophosphorylate in response to EGF, and transmit a mitogenic signal when stimulated by the appropriate ligand.

scholarly journals An Overview of In Vivo and In Vitro Models for Autosomal Dominant Polycystic Kidney Disease: A Journey from 3D-Cysts to Mini-Pigs

2020 ◽  
Vol 21 (12) ◽  
pp. 4537
Author(s):  
Svenja Koslowski ◽  
Camille Latapy ◽  
Pierrïck Auvray ◽  
Marc Blondel ◽  
Laurent Meijer
Keyword(s):  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Autosomal Dominant ◽  
In Vitro Models ◽  
Polycystic Kidney ◽  
Autosomal Dominant Polycystic Kidney ◽  
Stage Renal Disease ◽  
End Stage

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inheritable cause of end stage renal disease and, as of today, only a single moderately effective treatment is available for patients. Even though ADPKD research has made huge progress over the last decades, the precise disease mechanisms remain elusive. However, a wide variety of cellular and animal models have been developed to decipher the pathophysiological mechanisms and related pathways underlying the disease. As none of these models perfectly recapitulates the complexity of the human disease, the aim of this review is to give an overview of the main tools currently available to ADPKD researchers, as well as their main advantages and limitations.

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